Conferencing systems in which a plurality of devices are connected are well known. In the conferencing system, a presenter's device sends data such as images directly or indirectly to another device. The other device displays the data such as images that is sent from the presenter's device. Therefore, participants in a conference can view the same images by watching the display of each device.
FIG. 1 is a block diagram showing a conferencing system in which PC 101, which is a presenter's device, provides image data and voice data directly to other terminals (projectors and PCs) 102 to 110.
In addition, Patent Document 1 (JP-A No. 2006-279535) describes a conferencing system in which a plurality of terminals are connected to a conference server through a network. In this conferencing system, a presenter's device provides data such as images to a conference server. The conference server sends the data, which is provided from the presenter's device, to the other terminals.
In addition, conferencing systems in which a plurality of servers that are connected to terminals are connected to a conference server by a tree structure are also well known. FIG. 2 is a block diagram showing a conferencing system including a tree structure.
In FIG. 2, PC 201, which is a presenter's device, provides data such as images to projector 202, which is a conference server (conference master). Projector 202 provides the data to PC 203 and projector 204. Projector 204 provides the data to PC 205 and projectors 206 and 208. Projector 206 provides the data to PC 207. Projector 208 provides the data to PCs 209 and 210.
In these conferencing systems, one predetermined server always operates as a conference server.
Note that, in these conferencing systems, a PC (terminal) that serves as a presenter's device may be switched when there is a change of presenter.
[Patent Document 1] JP-A No. 2006-279535